The protective effect of breastfeeding on breast cancer

Public health researchers from Massey
University’s College of Health are calling for more
research into the possible protective effects of
breastfeeding on the recurrence of breast cancer in those
who have previously had the disease.

The paper, by Massey University PhD
candidate Narges Alianmoghaddam and her doctoral supervisor
Associate Professor Cheryl Benn along with colleagues Dr
Kaveh Khoshnood and Professor Holly Powell Kennedy from Yale
University, United States and Dr Minoor Lamyian from Tarbiat
Modares University, Iran, highlights the lack of research
relating to the potential protective effects of
breastfeeding after breast cancer.

“Our paper draws
attention to the high rate of mastectomy [the removal of the
entire breast] among premenopausal women across the world.
Removal of breasts eliminates the chance of future
breastfeeding, an optimal method of infant feeding. Although
we found several studies that show the possibility of
breastfeeding in breast cancer survivors, especially in
women who had breast conserving therapy [the removal of the
tumour only, with treatment via radiation therapy] or
unilateral mastectomy, we could not find any research on the
protective effect of breastfeeding after breast cancer
treatment regarding recurrence of breast cancer, or
developing breast cancer in the second breast for breast
cancer survivors. I would like to pursue this research
further, and hope to do so in my post-doctorate studies,”
Mrs Alianmoghaddam says.

She says the New Zealand
population suffers from high rates of obesity and breast
cancer, but breastfeeding could change that.
“Breastfeeding can help control obesity in our children
during their childhood and adulthood lives, but it also has
a protective impact on breast cancer in breastfeeding
mothers.

“Research shows, every 12 months of
breastfeeding in a woman’s lifetime leads to a significant
decline in the risk of developing invasive breast cancer
significantly. Through promoting breastfeeding, the New
Zealand health system could reduce rates of obesity and
breast cancer to a certain extent.”

Breast cancer is the
most common form of cancer affecting women worldwide. Recent
research published in The Lancet by Professor Cesar
Victora et al (University of Pelotas, Brazil), shows with
the current rate of breastfeeding, about 20,000 breast
cancer deaths are prevented globally, compared to if no
women breastfed.

“There is a chance an additional
20,000 deaths caused by breast cancer could be prevented
annually if the duration of breastfeeding increases to one
year per child amongst women in high-income countries
including New Zealand, or to two years per child in low and
middle income countries,” Mrs Alianmoghaddam says.

“In
New Zealand the rates of exclusive breastfeeding at six
months continue to decline, while health professionals,
especially midwives and lactation consultants, are actively
involved in promoting and supporting six months exclusive
breastfeeding.

“For example, in New Zealand in 2014,
more than eight out of ten infants were exclusively
breastfed at discharge from hospital, 42 per cent at three
months and only 16 per cent at six months. This number is
far below WHO’s health target of 50 per cent for six
months exclusive breastfeeding rates.”

Despite
widespread consensus regarding the health benefits of
exclusive breastfeeding for mother and baby, prevalence is
very low worldwide. According to the World Health
Organisation in 2016, increased breastfeeding rates can
avert 800,000 child deaths and provide savings of $300
billion (US) each year across the world. Consequently,
promoting breastfeeding especially increasing the rate of
exclusive breastfeeding at six months from the current rate
of 38 per cent to at least 50 per cent by 2025 has become a
global health target.

“The key conclusion of our paper
is the importance of breast cancer awareness in reproductive
age women. We should educate our girls and young women about
the method of breast self-examination and about the early
signs of breast cancer. We should educate mothers about the
health benefits of breastfeeding for themselves,
highlighting the protective effect of breastfeeding on the
occurrence of breast cancer in breastfeeding mothers. All
mothers should be encouraged and supported to breastfeed
their children for a longer duration regardless of having a
history of breast cancer,” Mrs Alianmoghaddam
says.

“Patients under 40 years of age make up about 5
per cent of the overall breast cancer population in the
United States. In New Zealand, in 2011, more than 11 per
cent of breast cancer patients were aged 25 to 44. However,
in developing countries, including Arab countries, that
rises to half of the breast cancer patients being in the
reproductive age range.

“For successful breast
conserving therapy, breast cancer needs to be detected in
the early stages, but detection in childbearing age women is
challenging. Although mammography can save lives via
diagnosing breast cancer about five years earlier than
clinical examinations, it is less efficient in reproductive
age women for several reasons including high rates of false
negative results, breast density and over-diagnosis,” she
says.

Mrs Alianmoghaddam is a Registered Midwife and PhD
candidate of Midwifery at Massey’s School of Public
Health. Her doctoral research is about promoting six months
exclusive breastfeeding in New Zealand. Her doctoral
supervisors are Dr Suzanne Phibbs, senior lecturer for the
School of Public Health, and Associate Professor Cheryl
Benn, a Registered Midwife an International Board Certified
Lactation Consultant (IBCLC).

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